#執行緒池一次性開闢一些執行緒，使用者給執行緒提交任務，執行緒任務的呼叫交給執行緒池來完成
#
# from concurrent.futures import ThreadPoolExecutor,ProcessPoolExecutor  #執行緒池和程序池
#
# def fn(name):
#     for i in range(1000):
#         print(name,i)
#
# if __name__ == '__main__':
#     #建立執行緒池
#     with ThreadPoolExecutor(50) as t:
#         for i in range(100):
 

#             t.submit(fn,name=f"執行緒{i}")
#      #等待執行緒名完畢，才繼續執行
#     print("over")

#思路
#1，如何提取單個頁面的資料
#2.上執行緒池，多個頁面同時抓取
import csv
import requests
from concurrent.futures import ThreadPoolExecutor
f=open("菜價.csv",mode="w",encoding="utf-8",newline='')
csvwriter=csv.writer(f)
def down_one_page(url):
    resp
 
=requests.get(url)
    for i in range(20):
        list=[]
        prodName=resp.json()["list"][i]['prodName']
        avgPrice=resp.json()["list"][i]['avgPrice']
        place=resp.json()["list"][i]['place']
        list.append(prodName)
        list.append(avgPrice)
        list.append(place)
        
 
print(list)
        csvwriter.writerow(list)




if __name__ == '__main__':
    #執行緒池 down_one_page("http://www.xinfadi.com.cn/getPriceData.html?current=1")
    with ThreadPoolExecutor(50) as t:
        for i in range(200): #爬取200頁資料
            t.submit(down_one_page,f"http://www.xinfadi.com.cn/getPriceData.html?current={i}")
    print("下載完畢")

多執行緒爬取新發地300頁菜價，速度得到很大的提升